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Biomedical subjects

J F Morrison

Publications and source records attributed to J F Morrison.

At least 91 records · Page 5Linked to original sources
PubMed1989

An electronic apparatus for early detection of changes in red cell content of blood during anaesthesia. A preliminary report.

An electronic apparatus was developed for anaesthetists to use to detect changes in red cell concentration during surgery. The mechanism is based on the relationship between the red cell content and the electrical conductivity of blood. In a pilot study of 170 blood samples, a correlation coefficient of 0.9806 was obtained between haematocrit and the instrument readings. To evaluate the instrument's performance in practice, and factors that might influence its readings, a series of 10 cases of aortic surgery were investigated. It is concluded that, although changes in electrolyte concentration, pH and temperature do affect the instrument's readings, these are insignificant compared with those of red cell content, and that the device can be used to indicate a drop in red cell concentration.

Anesthesiology↗
PubMed1989

Radiographic features and prognosis in bronchioloalveolar carcinoma; a local experience.

The prognosis of 20 patients with histologically proven bronchioloalveolar carcinoma was assessed in the light of their radiographic features and symptoms at presentation. Radiographically, half the patients were classified as having focal disease of which 60% were focal consolidation. Other focal presentations were, a mass lesion in three cases and a single 3 cm nodule in one case. Those with diffuse disease presented with either coarse widespread nodules or diffuse alveolar opacification with or without a focal area of consolidation. All patients were symptomatic at presentation but the severity of the symptoms bore no relation to the radiological findings. Seven cases with focal disease underwent thoracotomy, five of which had evidence of hilar and mediastinal lymph node involvement. They included a case presenting with a nodule, two with a mass and four with focal consolidation. The survival following surgery was generally better with those with a mass or nodule but one case with focal consolidation remains alive 10.5 years following surgery compared with the longest survivor of 4.5 years with a mass. Both these relatively long-term survivors had no histological evidence of hilar or mediastinal lymph node involvement compared with the other surgical cases. The median survival in cases without surgery was one month. The prognosis was better in patients with focal disease where surgery was performed and we feel that a local area of consolidation should be treated as focal disease and surgical resection considered for these patients.

Adenocarcinoma, Bronchiolo-Alveolar↗
PubMed1989

The effect of the circadian rhythm of vagal activity on bronchomotor tone in asthma.

1. The effect of the diurnal activity of the parasympathetic nervous system on bronchomotor tone and heart rate was studied in seven asthmatics with nocturnal asthma using both intravenous atropine and nebulised ipratropium at 04.00 h and 16.00 h. 2. A diurnal variation in vagal activity was demonstrated with higher vagal activity occurring at night. 3. There was a strong correlation between the initial response of both airway calibre and heart rate to vagal block both at 04.00 h and 16.00 h. However the duration of bronchodilation after vagal block was greater than with the heart rate suggesting differing sensitivities of pulmonary and cardiac muscarinic receptors to anticholinergic antagonists. 4. The bronchodilation seen after ipratropium was less than that after atropine suggesting that the intravenous route is preferable to study the physiological effect of vagal block in vivo.

Adolescent↗
PubMed1989

The distribution of beta-adrenoceptors in human cervix.

The distribution of beta-adrenoceptors in sections of human cervix taken at the proliferative phase of the menstrual cycle was studied using light-microscopic autoradiography. The radioligand [125I]iodocyanopindolol (125ICYP) was used to identify specific binding sites. Moderate density of labelling by 125ICYP was seen over smooth muscle and blood vessels. The most intense labelling, however, was seen over glands and surface columnar epithelium. The association of beta-adrenoceptors with glands and surface columnar epithelium suggests a possible adrenergic regulation of secretory function in the cervix.

Autoradiography↗
PubMed1989

The autoradiographic localization of calcitonin gene-related peptide and substance P receptors in human fallopian tube.

The binding of [125I] human alpha calcitonin gene-related peptide (hCGRP) and [125I]Bolton-Hunter-labelled substance P (BH-SP) to human fallopian tube tissue sections was characterized and the respective binding sites were localized by light-microscopic autoradiography. The hCGRP binding sites were associated with the muscularis, lamina propria and vascular smooth muscle, the latter being the most intensely labelled. BH-SP binding sites were associated only with blood vessels. This labelling was intense, and appeared to be restricted to the vascular endothelium. These results suggest that calcitonin gene-related peptide and substance P may act together to regulate local blood flow and plasma extravasation.

Autoradiography↗
PubMed1989

The presence of beta-adrenoceptors in rat endometrium is dependent on circulating oestrogen.

It has been proposed that the change in sensitivity of the uterus to catecholamines during the oestrous cycle may result from changes in beta-adrenoceptor density in the myometrium. In the present work we applied the technique of light-microscopic autoradiography using the radioligand [125I]iodocyanopindolol to study the density and distribution of beta-adrenoceptors in the rat uterus during the normal oestrous cycle, following ovariectomy, and after ovariectomy with oestradiol replacement. We found that beta-adrenoceptor density in the endometrium, but not the myometrium, varied during the oestrous cycle, being highest during pro-oestrous. The endometrium of the ovariectomized rats was devoid of any beta-adrenoceptors, whilst that of the oestradiol-treated rats was very intensely labelled. Following ovariectomy there was an increase in beta-adrenoceptor density in the myometrium, but this was not observed in the animals given oestradiol replacement. It appears that both the presence and density of beta-adrenoceptors in rat endometrium is dependent on circulating oestrogens.

Animals↗
PubMed1988

Treatment of anismus in intractable constipation with botulinum A toxin.

In seven patients with anismus the striated sphincter muscle complex was selectively weakened by local injection of Clostridium botulinum type A toxin. Symptom scores improved significantly and correlated with a significant reduction in the maximum voluntary and canal squeeze pressure and a significant increase in the anorectal angle on straining. Botulinum A toxin seems to be promising treatment for some patients with anismus.

Adult↗
PubMed1988

Dihydrofolate reductase from Escherichia coli: the kinetic mechanism with NADPH and reduced acetylpyridine adenine dinucleotide phosphate as substrates.

Kinetic studies on the reaction catalyzed by dihydrofolate reductase from Escherichia coli have been undertaken with the aim of characterizing further the kinetic mechanism of the reaction. For this purpose, the kinetic properties of substrates were determined by measurement of (a) initial velocities over a wide range of substrate concentrations and (b) the stickiness of substrates in ternary enzyme complexes. Stickiness is defined as the rate at which a substrate reacts to give products relative to the rate at which that substrate dissociates. Stickiness was determined by varying the viscosity of reaction mixtures and the concentration of one substrate in the presence of a saturating concentration of the other substrate. The results indicate that NADPH is sticky in the enzyme-NADPH-dihydrofolate complex, while dihydrofolate is much less sticky in this complex. At higher concentrations, NADPH functions as an activator through the formation of an enzyme-NADPH-tetrahydrofolate from which tetrahydrofolate is released more rapidly than from an enzyme-tetrahydrofolate complex. Higher concentrations of dihydrofolate also cause enzyme activation, and it appears that this effect is due to the ability of dihydrofolate to displace tetrahydrofolate from a binary enzyme complex through the formation of a transitory enzyme-tetrahydrofolate-dihydrofolate complex. As NADPH and dihydrofolate function as activators and as NADPH behaves as a sticky substrate, the kinetic mechanism of the dihydrofolate reductase reaction with the natural substrates is steady-state random. By contrast with NADPH, reduced 3-acetylpyridine adenine dinucleotide phosphate exhibits only slight stickiness and does not function as an activator.(ABSTRACT TRUNCATED AT 250 WORDS)

Deuterium↗
PubMed1988

Mechanism of the reaction catalyzed by dihydrofolate reductase from Escherichia coli: pH and deuterium isotope effects with NADPH as the variable substrate.

The variations with pH of the kinetic parameters and primary deuterium isotope effects for the reaction of NADPH with dihydrofolate reductase from Escherichia coli have been determined. The aims of the investigations were to elucidate the chemical mechanism of the reaction and to obtain information about the location of the rate-limiting steps. The V and V/KNADPH profiles indicate that a single ionizing group at the active center of the enzyme must be protonated for catalysis, whereas the Ki profiles show that the binding of NADPH to the free enzyme and of ATP-ribose to the enzyme-dihydrofolate complex is pH independent. From the results of deuterium isotope effects on V/KNADPH, it is concluded that NADPH behaves as a sticky substrate. It is this stickiness that raises artificially the intrinsic pK value of 6.4 for the Asp-27 residue of the enzyme-dihydrofolate complex [Howell, E. E., Villafranca, J. E., Warren, M. S., Oatley, S. J., & Kraut, J. (1986) Science (Washington, D.C.) 231, 1123] to an observed value of 8.9. Thus, the binary enzyme complex is largely protonated at neutral pH. The elevation of the intrinsic pK value of 6.4 for the ternary enzyme-NADPH-dihydrofolate complex to 8.5 is not due to the kinetic effects of substrates. Rather, it is the consequence of the lower, pH-independent rate of product release and the faster pH-dependent catalytic step. At neutral pH, the proportion of enzyme present as a protonated ternary enzyme-substrate complex is sufficient to keep catalysis faster than product release.(ABSTRACT TRUNCATED AT 250 WORDS)

Aspartic Acid↗
PubMed1988

Parasympathetic nervous system in nocturnal asthma.

To investigate the effect of vagal blockade with atropine on nocturnal fall in peak expiratory flow rate 10 patients with asthma who had a diurnal variation in peak expiratory flow rate of greater than 20% were given 30 micrograms/kg of intravenous atropine or a placebo at 4 am and 4 pm. Vagal blockade caused significant bronchodilatation at 4 am and 4 pm (peak expiratory flow rate rose from 260 to 390 l/min at 4 am and 400 to 440 l/min at 4 pm) and significantly increased the pulse rate from 60 to 121 beats/minute at 4 am and from 76 to 122 beats/minute at 4 pm. Nocturnal asthma was almost totally reversed, implying that vagal mechanisms are fundamental in its pathophysiology. Other mechanisms--diurnal changes in plasma adrenaline concentration, the activity of non-adrenergic non-cholinergic nerves, and circadian rhythms of inflammatory mediator activity--may also be implicated.

Adult↗
PubMed1988

Prospective study of the effects of postanal repair in neurogenic faecal incontinence.

The most important factor associated with a good result in the surgical treatment of neurogenic faecal incontinence by postanal repair is considered to be restoration of the obtuse anorectal angle. Sixteen patients (14F:2M; median age 59 years) with neurogenic faecal incontinence confirmed by a raised fibre density in the external anal sphincter underwent postanal repair. Pre- and postoperative manometric assessment was performed in 16 and radiological assessment in 12. Normal ranges for these parameters were established in age and sex matched control subjects. Continence was improved in 14 (88 per cent) patients, 6 (38 per cent) of whom regained normal continence, at a minimum of 15 months follow-up. A successful outcome was associated with no significant change in basal (pre-operative 35 (10-85) cmH2O, postoperative 44 (12-105) cmH2O; n.s.) or voluntary (pre-operative 43 (5-150) cmH2O, postoperative 32 (12-180) cmH2O; n.s.) components of anal canal pressure. There was a small but significant increase in sphincter length (pre-operative 2 (0-3) cm, postoperative 2.5 (0-3.5) cm; P less than 0.01). There was no significant change in the anorectal angle at rest (pre-operative 96 (90-110) degrees, postoperative 107 (79-118) degrees; n.s.) in the patients in whom continence was restored and five of these patients had resting anorectal angles within the normal range (75-94 degrees). Thus postanal repair need not be restricted to patients with widening of the anorectal angle since its beneficial effects do not appear to be related to reduction of this angle.

Aged↗
PubMed1988

A comparison of the distribution of substance P and calcitonin gene-related peptide receptors in the rat bladder.

Binding of [125I]Bolton-Hunter labelled substance P (BH-SP) and [125I]human alpha-calcitonin gene-related peptide (h alpha CGRP) to rat bladder tissue sections was characterized and the respective binding sites localized by light-microscopic autoradiography. BH-SP binding sites were localized to epithelium, blood vessels and smooth muscle while hCGRP binding sites were present only over the epithelium. These results suggest that the range of biological actions of substance P and calcitonin gene-related peptide, which may be co-released from the same afferent terminals, might be determined by the different distributions of their respective receptors.

Animals↗
PubMed1988

Reproducibility of walking test results in chronic obstructive airways disease.

Thirty six patients with chronic airflow obstruction were studied to examine (1) the reproducibility and order effect of repeated walking tests when performed over consecutive days or consecutive weeks; (2) the correlation between walking distance and spirometric measurements; and (3) the effect of static visual clues on performance. In study 1, where 12 patients performed 12 walks over three consecutive days, five minute walking distance increased by 33% between walks 1 and 12, half of the increase occurring after the first three walks. In study 2, where 24 patients performed 12 walks over four consecutive weeks, five minute walking distance increased by 8.5% between walks 1 and 12. A learning effect was seen over the first nine walks. Static visual clues to performance did not affect the distance walked. Spirometric measurements showed no order effect in either study. Although walking distance correlated significantly with FEV1, forced vital capacity, and peak expiratory flow, these measurements were poor predictors of exercise performance. The learning effects seen on repeated performance of walking tests over short intervals should be considered when an individual's response to treatment is being interpreted. When walking tests are used in clinical trials a placebo group or randomised crossover design is essential.

Aged↗
PubMed1987

An excitatory influence of dorsolateral pontine structures on urinary bladder motility in the rat.

The effects of electrical stimulation of dorsolateral pontine structures on urinary bladder motility have been compared with those of microinjection of an excitatory amino acid, DL-homocysteic acid (DLH), which is believed to activate neuronal cell bodies but not axons. Increases in the intravesical pressure (IVP), indicative of urinary bladder contractions, were observed following low intensity (less than 50 microA) electrical stimulation in the brachium conjunctivum (BC) and the surrounding parabrachial nucleus (PBN). In contrast, increases in IVP evoked by DLH were observed only after its injection into a localised area just dorsal to the BC, in the region of the lateral parabrachial nucleus. These results suggest that cell bodies of neurones with an excitatory influence on the urinary bladder are located in restricted regions of the PBN, dorsal to the BC.

Animals↗
PubMed1987

Anorectal function in the solitary rectal ulcer syndrome.

The anorectal function of nine patients with solitary rectal ulcer syndrome (SRUS) (5 F: 4 M, median age, 27 (range, 19-41 years) and nine control subjects (5 F: 4 M, median age, 47 (35-66) P less than 0.01) has been investigated by a new technique that radiologically visualizes the anorectum during voiding of a semisolid contrast medium, while simultaneously measuring intrarectal pressure and anal sphincter EMG activity. A degree of rectal prolapse was demonstrated in eight of the SRUS patients; six of these lesions were clinically occult. Abnormal failure of the anal sphincter to relax on voiding was present in seven of the SRUS patients. These abnormalities resulted in the SRUS patients requiring a greater increase in intrarectal pressure (median, 100 cm water) to void than the control subjects (median, 65 cm water, P less than 0.01). This combination of high intrarectal pressure and rectal prolapse during staining seems to be the cause of SRUS.

Adult↗